what occurred in 1968 besides the assassinations that had a impact for african american electoral politics?

Answer 1

Tom Brokaw did a lenghty program last night on CNN about 1968. I'm sure they'll re-air it. It should answer all your questions. He's also written a book.

Answer 2

Quite simply it was the first presidential election after the signing of the Voting Rights Act of 1965 that made all the nasty voting practices that disenfranchised African Americans illegal. Southern states could no longer re-arrange their voting districts to take best advantage of white populations and isolate black ones. Literacy and other illegal requirements were banned from being used at the polling place. There were a lot of other provisions but this cleared the way for many, many more Black and Latino people to have their say in what turned out to be a world-changing election.